Deformation recording without electrical charging



k-- July 7, 1970 J. GAYNOR ETAI- 3,519,422

DEFORMATION RECORDING WITHOUT ELECTRICAL CHARGING Filed D90. 29, 1965 5 Sheets-Sheet 1 RECORDING MEMBER OF TEMPERATURE STABLE SUPPORT COATED WITH A THIN LAYER OF THERMOPLASTIC RESIN CONTAINING A PHOTOSENS/TIVE SUBSTANCE WHICH PRODUCES ELECTRICAL FORCES WHEN ACTIVATING RADIATION IMPINGES ON THE LAYER.

EXPOSURE OF THE RECORDING MEMBER TO AN IMAGE PATTERN OF THE ACTIVATING RADIATION PRODUCED BY LOCATING A PHOTOGRAPH/C NEGATIVE BETWEEN THE RECORDING SURFACE AND SOURCE OF RADIATION. A LATENT FORCEYPATTERN OF THE IMPINGING RADIATION FORMS IN THE THERMOPLASTIC LAYER FROM THE EXPOSURE.

DEVELOPMENT OF PHYSICAL DEFORMATIONS ON THE SURFACE OF THE THERMOPLASTIC LAYER CORRESPONDING TO THE LATENT IMAGE PATTERN IS PRODUCED BY HEATING THE EXPOSED LAYER TO THE PLASTIC CONDITION. THE FORCES OF THE LATENT IMAGE PATTERN EXERT FORCES WHICH SELECTIVELY DEFORM THE SURFACE OF THE SOFTENED THERMOPLASTIC LA YER.

INVENTORS JOSEPH GAYNOR GORDON J. SEWELL ATTY July 7, 1970 J GAYNQR ET AL DEFORMATION RECORDING WITHOUT ELECTRICAL CHARGING 3 Sheets-Sheet 2 July 7, 1970 GAYNOR ET AL CORDING WITHOUT ELECTRICAL CHM DEFORMATION RE 5 Sheets-Sheet 5 Filed Dec.

Eva A United States Patent 3,519,422 DEFORMATION RECORDING WITHOUT ELECTRICAL CHARGING Joseph Gaynor, Schenectady, and Gordon J. Sewell, Al-

bany, N.Y., assignors to General Electric Company, a corporation of New Yorlr Continuation-impart of application Ser. No. 231,138, Oct. 17, 1962. This application Dec. 29, 1965, Ser. No. 517,315

Int. Cl. G03g 13/12; B41m 5/18; Gllb US. C]. 96-27 3 Claims ABSTRACT OF THE DISCLOSURE A recording method is described in which a recording member comprising a temperature stable support coated with a thin layer of thermoplastic resin containing a photosensitive substance which produces electrical forces in response to the impingement of activating radiation thereon is exposed to a pattern of activating radiation to produce an electric force pattern in the thermoplastic layer corresponding to the radiation and developing a pattern of physical deformation corresponding to the force pattern without subjecting the recording member to an electric charging operation.

This application is a continuation-in-part of the copending application of Joseph Gaynor and Gordon J. Sewell, Ser. No. 231,138 filed Oct. 17, 1962 for Information Recording (now abandoned).

This invention relates to a recording method and system for producing a selective electrical force pattern in a dielectric material, and to a recording medium incorporating such dielectric material therein, and to a record produced thereby. More particularly, the invention pertains to an information storage method and system for establishing an electrical force pattern in a dielectric material by exposing the dielectric material to activating radiation in a desired pattern, and to a method and system for developing this pattern into a visible reproduction thereof, the information in the visible reproduction being retrievable as an optical image or an electrical signal.

A recording system for producing a visible image in the form of light-modifying deformations on the surface of a dielectric medium has been described in a. copending patent application of Sterling P. Newberry, Ser. No. 862,249, filed Dec. 28, 1959, and assigned to the assignee of the present invention. In the embodiments illustrated in that application, an electrostatic charge pattern of the information to be recorded is produced on a photosensitive element and thereafter physically transferred to the surface of a thermoplastic storage member with the assistance of a polarizing voltage. The electrostatic charge pattern is produced on the surface of the photosensitive element by first uniformly charging this member with a corona discharge mechanism or equivalent means and thereafter selectively discharging the uniform charge pattern by exposure to a light image. The impinging light so modifies the electrical characteristics of the photosensitive element that portions of the charge leak off the surface in accordance with the light characteristics of the image. The charge pattern transferred to the surface of the thermoplastic storage member is converted to a visible image by softening the thermoplastic material so that the electrostatic forces due to the charge pattern deform the surface to form corresponding deformations. The information storage member for this process may be transparent in nature so that retrieval of the information stored on the surface of the member may be obtained by projecting a beam oflight through the lightmodifying depressions. The modified light rays emerging 3,519,422 Patented July 7, 1970 from the transparent storage member may then be projected onto a viewing surface or converted to an electrical signal with a photoelectric device for readout.

In another co-pending patent application entitled Information Storage on a Deformable Medium, by Joseph Gaynor, Ser. No. 79,260, filed Dec. 29, 1960, now Pat. No. 3,291,601, granted Dec. 13, 1966, and assigned to the assignee of the present invention a different system of information recording is disclosed for storing the information in the form of light-modifying deformations on a surface of a deformable photoconductive member. In the system, the information to be stored is transmitted by activating radiation directly onto a uniformly charged deformable photoconductive member and by reason thereof, the photoconductive member becomes selectively discharged according to the pattern of the activating radiation. The selectively charged member is developed by softening the deformable medium so that forces of the electrostatic charge pattern deform the medium in accordance therewith. Retrieval of the information stored in the deformed storage member may again be obtained by projecting a light beam through the medium for direct optical readout on a viewing surface or for conversion to electrical signals by means of the aforementioned type light-sensing devices.

While generally satisfactory recordings are provided by the information storage processes above described, there is need for electrostatic charging in the practice of each process. The requirement for electrostatic charging adds one or more steps to the information recording process and generally necessitates high voltage electrical equipment to carry out this portion of the process. It would constitute a general advance in the entire field of information recording if a selective charge pattern could be established in the information storage member without need for charging the member by any electrical means. It will also constitute a general advance in the art of information recording if a selective electrical force pattern could be established in a recording member responsive to light-modulation alone that could be developed directly into deformations on the surface of the member.

It is an important object of the invention to provide a recording method and system for storing information in a dielectric material directly from activating radiation projected onto the surface of the dielectric material in the desired pattern to be recorded.

Another object of the invention is to provide a recording method and system for storing information in a dielectric material having incorporated therein a photosensitive substance characterized by the production of an electrical force pattern in response to exposure thereof to activating radiation in the selective pattern to be recorded.

In connection with the foregoing object, it is another object of the invention to provide a recording method and system wherein the dielectric material is a liquid, the visible image being produced on the surface of the liquid dielectric material that is deformed by the force pattren produced by exposure to a selective pattern of the activating radiation.

Still another object of the invention is to provide a method and system for storing information in a thermoplastic dielectric photosensitive medium characterized by the production of an electrical force pattern in response to exposure thereof to activating radiation, the thermoplastic dielectric material being heated to the plastic condition so that electrical forces therein corresponding to a selective pattern of activating radiation deforms a surface of the dielectric material to produce a corresponding visible image thereon.

In connection with the foregoing object, it is another object of the invention to provide a method and system of recording information of the type set forth wherein the electrical forces persist in the medium even after repeated heating thereof to the plastic condition and cooling thereof to the solid condition, whereby the visible image on the surface of the thermoplastic dielectric material can be alternately erased and redeveloped.

A further object of the invention is to provide a method and system of recording and changing a visible image on a medium of the type set forth, wherein a first electrical force pattern is established in the dielectric material, and thereafter a predetermined area thereof is permanently erased by heating the dielectric material to the plastic condition, and thereafter exposing the predetermined area of the surface to a second selective pattern of the activating radiation to produce a corresponding second persistent electrical force pattern therein.

A still further object of the invention is to provide a recording member that is useful in the recording method and system set forth above, the recording member comprising a layer of dielectric material having incorporated therein a photosensitive substance characterized by the production of electrical forces in response to exposure thereof to activating radiation.

A still further object of the invention is to provide a record formed by the method and system set forth above and utilizing the recording member of the present invention, the record having information stored thereon in the form of surface deformations that are intaglio reproductions of the subject matter to be stored.

Further features of the invention pertain to the particular arrangement of the steps of the method and the parts of the system and the composition and construction of the recording member and record, whereby the aboveoutlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic perspective view, partly in section, of a first preferred form of a recording member useful in the present invention;

FIG. 2 is a diagrammatic perspective view showing an assembly of the recording member of FIG. 1 with an overlying photographic negative and source of activating radiation for exposing selected areas of the surface of the recording member to activating radiation;

FIG. 3 is a diagrammatic perspective view of the assembly of a heat source with the exposed recording member and schematically illustrating the surface deformations in the recording member after development thereof by heating;

FIG. 4 is a diagrammatic view of a first preferred form of system for exposing, heat developing and cooling a continuous strip of recording member in accordance with the present invention;

FIG. 5 is an enlarged view in vertical section and diagrammatic in character through the system of FIG. 4 along the line 5-5 thereof and illustrating the exposure of the recording member to the activating radiation;

FIG. 6 is an enlarged view in vertical section and diagrammatic in character through the system of FIG. 4 along the line 6-6 thereof and illustrating the internal charge pattern in the recording member after exposure thereof to activating radiation;

FIG. 7 is an enlarged view in vertical section and diagrammatic in character through the system of FIG. 4 along the line 77 thereof and schematically illustrating the deformations in the surface of the recording member after development thereof;

FIG. 8 is a diagrammatic view of a second preferred form of system for exposing, heating, developing, and cooling another preferred form of recording member in accordance with the present invention;

FIG. 9 is an enlarged view in vertical section and diagrammatic in character through the system of FIG. 8 along thel inc 99 thereof and illustrating the exposure of the recording member to the activating radiation;

FIG. 10 is an enlarged view in vertical section and diagrammatic in character through the system of FIG. 8 along the line 1010 thereof and illustrating the internal charge pattern in the recording member after exposure thereof to activating radiation; and

FIG. 11 is an enlarged view in vertical section and diagrammatic in character through the system of FIG. 8 along the line 11-11 thereof and schematically illustrating the deformations in the surface of the recording member after development thereof.

Briefly, a selective electrical force pattern suitable for information recording may be established in a dielectric material containing a photosensitive substance upon exposure of the material to activating radiation in the desired image pattern. The individual photocharges generated by exposure to a pattern of activating radiation defining the image are electrical in nature and can be made to exert sufiicient forces in the surrounding dielectric material to produce deformations on the surface of the member.

In one preferred method of the invention, minute lightmodifying deformations are produced on the surface of a thermoplastic layer of dielectric material containing a photosensitive substance simply by heating the thermoplastic layer after exposure to activating radiation in the image pattern. The recording system for the process need comprise no more than the recording member, illuminating means for exposing the recording member to activating radiation in an image pattern, and heating means for softening the thermoplastic layer of the recording member. Direct conversion of the electrical force pattern in the dielectric material to a visible image by energy means alone obviates conventional development agents including solvents, charged powders, and the like, along with the process steps and apparatus now used for development of a visible image from a latent exposure. The deformation images produced exhibit gray scale together with resolution capability adequate for microbit storage so that the present process has greater potential utility than conventional xerography, thermograp-hy, and many other known information storage processes. While the present recordings are permanent under ordinary ambient conditions, the stored information can be erased by heating the deformed thermoplastic layers of the recording member to the plastic state for a sufficient period of time to permit leveling of the softened material. It is contemplated, therefore, to record different information on the same record ing member by this procedure so that complete erasure and recording may be accomplished a number of times as well as with editing or revision of selected portions in a given recording.

The invention may be practiced in one of its preferred embodiments as illustrated in FIGS. 1 to 3 of the accompanying drawings which depict schematically a system and method of recording for production of a deformation image on the surface of a recording member responsive to a projected optical image. Generally, the illustrated embodiment utilizes a recording member of the invention, illuminating means for exposing the recording member to activating radiation in an area image pattern to establish an electrical force pattern in the recording member, and energy means for converting the electrical force pattern to a visible image on the surface of the recording member.

In FIG. 1, the recording member 1 is illustrated comprising a support 2 of temperature stable material which can be paper, a synthetic organic polymer, metal, ceramic, or other like material, which is coated with a thin layer 3 of a dielectric material, specifically a thermoplastic resin, containing a photosensitive substance disposed therein. The support member 2 may conveniently be fabricated of optically clear material to provide transparency of the final record if desired. The recording of information is achieved on the recording member 1 according to the invention by initially exposing the thermoplastic layer 3 to activating radiation which has been modulated in the desired image pattern to produce a latent electrical force image corresponding to the pattern of exposure. A convenient arrangement for creating a latent image pattern in the recording member 1 appears in FIG. 2 wherein a modulation means is inserted directly in the path of activating radiation emanating from a lamp source 5 which illuminates the recording member 1. The modulation means may comprise a photographic negative 4 or some other member containing the information to be recorded on the recording member 1 and which is transparent to the particular radiation being employed in the areas defining the image to be recorded. Alternatively, other known means for modulating a beam of radiation may be used for exposing the recording member 1, if advantageous to do so in a particular form of recording. The particular photographic negative 4 depicted in FIG. 2 for illustrative purposes contains an image comprising a series of parallel spaced elongated opaque strips oriented on an otherwise transparent background thus forming transparent elongated strips 6 thereon. Projection of activating radiation through the negative 4 from the source 5 onto the thermoplastic layer 3 of the recording member 1 produces a latent force pattern 6 in the layer 3 having a point-by-point correspondence with the image 6 of the negative 4. The latent image is formed in the interior of the thermoplastic layer 3 so that the individual electrical forces are not discharged by electrical grounding of the surfaces of the recording member 1. Development of the force pattern to produce a visible deformation image, such as in the manner hereinafter more fully described, may be achieved after storage periods of twenty-four hours and longer at the ordinary ambient conditions since the individual forces have been found not to migrate appreciably during such interim storage. While a conventional light projection system including the photographic negative 4 and the light source 5 has been depicted in FIG. 2 for simplicity in illustrating one means to establish a selective force pattern in the recording member 1, other known means for modulating the activating radiation in an image pattern also produce satisfactory results. For example ordinary contact printing wherein a photograghic negative or other light-modulating pattern is placed directly on the recording member 1 and the composite arrangement thereafter exposed to activating radiation, produces a desirable selective force pattern in the recording member 1. Likewise, a selective force pattern may also be established in the recording member 1 with an optical image projected from a cathode ray tube having glass fibers extending through the face plate of the tube in accordance with the image appearing on the tube face.

Conversion or development of the latent image defined by the force pattern in the recording member 1 to surface deformations thereon corresponding to the force pattern may be obtained by heating the exposed recording member 1 in the manner shown in FIG. 3. To this end, a heat energy means, which may consist of an ordinary infrared heating lamp 7, is suitably disposed with respect to the exposed recording member 1 to heat the thermoplastic layer 3 thereof to the plastic condition, whereupon the forces of the pattern prodiuce surface deformations 8 thereon corresponding to the force pattern therein. Subsequent cooling of the deformed thermoplastic layer 3 to the solid condition preserves the deformations permanently unless deliberately erased by reheating to a sufficiently elevated temperature for a long enough time period to allow leveling of the thermoplastic layer 3 in the plastic condition thereof. Thus, controlled heating of the recording member 1 produces deformations therein after exposure thereof to activating radiation, or alternatively,

erasure of a deformed recording member 1, dependent upon the temperature-time conditions of heating for the particular thermoplastic resin in the upper layer 3 of the recording member 1. As a general rule, erasure is conducted at higher temperatures than those employed for conversion or developing, since it is not necessary fully to fuse the thermoplastic resin before the electrical force pattern can deform the resin in the plastic set thereof.

The first preferred embodiment of the recording member 1 and the method of making the same will now be described in detail, the support 2 being rigid and the layer 3 being a solid dielectric material, the photosensitive substance utilized therein being a halogenated hydrocarbon and specifically a polyhalogenated hydrocarbon.

EXAMPLE 1 The support 2 is constructed of glass. A coating composition for forming the member layer 3 was compounded by dissolving five parts by weight of iodoform and 100 parts by weight of a commercially available polystyrene in benzene, the solution containing 25 percent by weight of polystyrene solids, at room temperature with mechanical agitation until a homogeneous liqluid solution was obtaincd. Fabrication of the recording member 1 from. the prepared coating composition consisted of placing a uniform layer of the coating composition on the glass support 2 and evaporating the benzene solvent by air drying. The resultant layer 3 had a thickness of 25 microns.

The polystyrene in the coating composition had an average molecular weight of approximately 20,000, an electrical resistivity at ambient temperature of about 10 ohm-centimeters, and had a softening temperature, i.e., reached the plastic condition, at a temperature of approximately C.

The thickness of the thermoplastic layer 3 is preferably in the range from about 15 microns to about 50 microns. In general, it is advisable to maintain the thickness of the layer 3 no less than 5 microns in order to obtain a well-defined deformation image. At thicknesses greater than about 50 microns for the layer 3, the speed of recording may be faster however solvent removal becomes more difiicult and flexibility is reduced.

As illustrated in Example 1, the iodoform is the photosensitive substance that is characterized by the production of electrical forces in the layer 3 in response to exposure thereof to activating radiation from the light source *5, which is a tungsten filament lamp of a standard construction. The concentration of the iodoform in the formulation of Example 1 is approximately 5 percent by weight of the thermoplastic layer 3. Lesser concentrations of the iodoform can be utilized, but the sensitivity of the layer 3 to activating radiation is correspondingly reduced. Slightly greater concentrations of the iodoform of the layer 3 may likewise be used; however, the iodoform is a plasticizer for the thermoplastic layer 3, whereby if a substantially larger concentration of iodoform is utilized,-

the plastic condition of the layer 3 is obtained at substantially, lower temperatures, whereby the deformations 8 in the exposed and developed layer 3 are not so permanent and are subject in fact to cold flow as well as erasure at the higher temperatures. In addition, the iodoform has a limited solubility in benzene and substantially greater concentrations thereof cannot be retained in solution in the coating composition without modification of the solvent system thereof.

The recording member 1 prepared as in Example 1 above was then employed to copy an image contained on the photographic negative 4 by projecting the image onto the thermoplastic layer 3 with an ordinary 300 watt slide projector for an exposure time of 30 seconds as shown in FIG. 5. There resulted a latent charge image illustrated in FIG. 6 in the thermoplastic layer 3 of the recording member 1 that was developed by heating the recording member 1 by means of the infrared lamp 7 to a temperature in the range from 80-120 C., i.e., until the thermoplastic resin in the layer 3 was in the plastic state, whereupon the deformations 8 were formed in the layer 3 corresponding to the projected image 6. The recording member 1 was then cooled to ambient temperature and the deformations 8 were permanently preserved as shown in FIG. 7. The recording member 1 is further reuseable, the deformations 8 being erased by heating the layer 3 in an oven at 80 C. for ten minutes; after erasure, the recording member 1 was again exposed to the activating radiation of the source 5, to the photographic film 4 to form a corresponding charge pattern 6' therein, and thereafter the force pattern 6' was converted to deformations 8 by heating using the infrared source 7. Care must be taken to erase the deformations on the recording member 1 at temperatures below the evaporation temperature of the iodoform. A recording member 1 made in accordance with Example 1 av be successfully exposed, developed, and erased as many as eight times.

The information stored in the surface deformations 8 on the recording member 1 can be conveniently retrieved directly by means of a schlieren optical system. Since both the support 2 and the layer 3 of the recording member 1 of Example 1 are transparent to visible light, a light beam was projected through the recording member 1, the light beam being refracted and/or diffracted by passage through the deformations. When the light beam was passed through a schlieren bar arrangement and onto a viewing screen, there was produced an optical image with a light intensity variation that is a function of the depth of the deformations 8 on the surface of the recording member 1. Complete operating details of the transmission type multiple bar schlieren optical readout system suitable for retrieving the information stored as the deformations 8 on the surface of a transparent recording member 1 may be found in U.S. Pat. No. 3,113,- 179 granted Dec. 3, 1963 to William E. Glenn, Jr., and assigned to the assignee of the present invention.

Production of an optical schlieren image having gray scale is possible by utilizing the above-described recording member 1 in accordance with Example 1 and the abovedescribed recording process by inserting a grid element, such as a screen, between the image being copied, for example the photographic film 4, and the recording member 1 during exposure thereof to the activating radiation from the light source 5. When screen sizes less than about 200 mesh U.S. screen size are utilized, the schlieren image projected by transmitting light through the deformation recording member 1 exhibits fewer shades of gray than the original negative 4. As the mesh size utilized increases, the number of shades of gray exhibited in the schlieren projected image are also increased. When a 750 mesh screen size is utilized, at least eight shades of gray are resolved.

As was noted above when first describing FIGS. 1 to 3, another preferred form of the recording member 1 is that wherein the support 2 is formed of a flexible material, such as a flexible thermoplastic resin. The following is an example of such a recording member.

EXAMPLE 2 In forming the recording member 1 of this example, a suitable material for the support 2 comprises a thermoplastic resin that requires a higher temperature to reach the plastic condition thereof than the composition of the layer 3, thereby to permit development of a visible image in the layer 3 during the recording process utilizing heat development systems. A preferred material for the sup port 2 is a commercially available transparent polyethylene terephthalate film or tape; preferably the tape has a flexibility such as to allow winding thereof around small diameter mandrels, i.e., mandrels having a diameter of inch, which is the usual requirement for the conventional projection machines, whereby the support 2 in the form of a flexible thermoplastic resin should have a thickness in the range from about microns to about microns. The recording layer 3 has the same composition as, and is made in accordance with Example 1 above. As pointed out above, the layer 3 preferably has a thickness in the range from about 5 to about 50 microns.

There is illustrated in FIG. 4 of the drawings a system 20 particularly adapted for exposing and developing a recording member 1 that is flexible in character as described above in Example 2. The system 20 includes a base 21 having an upstanding support 22 at the lefthand end thereof and carrying at the upper end thereof a shaft 23 for supporting a supply roll 24 of the flexible recording member 1. The base 21 also has a second upstanding support 25 at the right-hand end thereof and carrying at the upper end thereof a shaft 26 for supporting a takeup roll 27 for the flexible recording member 21. The shaft 26 also carries a drive pulley 28 that is driven by a drive motor 30 to cause the recording member 1 to move from the supply roll 24 to the takeup roll 27. The motor 30 is mounted upon the base 21 and has an output shaft 31 carrying a drive pulley 3 2, a flexible belt 33 interconnecting the pulleys 28 and 32, whereby the drive motor 30 can drive the takeup roll 27 as illustrated. Power for operation of the motor 30 is derived from a commercial 236 volt, 60 cycle A-C Edison supply designated by the numeral 40 and including a terminal board B carrying connections for the outer power conductors L1 and L2 that are connected respectively to conductors 41 and 42 and carrying a connection for the inner neutral conductor N that is grounded. The motor 30 has a pair of power input terminals 34 and 35, the terminal 34 being connected to the line conductor 41 and the terminal 35 being connected to the line conductor 42 via a control switch 43 and a conductor 44.

The system 20 also includes an exposure station 50 at which there is provided a standard 51 that holds a support 5-2 overlying a section of the recording member 1, the support 52 being adapted to hold in operative position above a section of the recording member 1, the photographic negative 4. Disposed above the support 52 and spaced therefrom is a source of activating radiation in the form of a light bulb 53 of the tungsten filament type mounted upon a standard 54, the bulb 53 being provided with the usual socket having a pair of electrical input terminals 55 and 56, the terminal 55 being connected to the neutral conductor N and the terminal 56 being connected to the line conductor 41 through a control switch 45 and a conductor 46. The light bulb 53 emits essentially white light, and it will be understood that the photographic negative 4 has certain portions 6 thereof (see FIG. 5) that are transparent to the activating radiation or light (designated by the numeral 57 in FIG. 5) from the light bulb 53, and further the support 52 is transparent to the activating radiation 57 from the light bulb 53, and is preferably formed of glass. As is illustrated in FIG. 5, the photographic negative 4 has portions opaque to the light 57 between the portions 6 that are transparent to the light 57, the transparent portions 6 transmitting the light 57 which is directed thereupon onto certain predetermined areas of the upper surface of the layer 3 and in point-by-point correspondence to the transparent areas 6 in the photographic negative 4. It will be understood that the length of the exposure of the recording member 1 to the activating radia tion 57 through the photographic negative 4 is determined by the length of the time that the switch 45 is closed. After exposure at the station 50, there are thought to be present within the upper layer 3 a plurality of pairs of charges in the areas or zones 6' corresponding to the areas struck by the activating radiation 57, as illustrated in FIG. 6. As has been pointed out hereinabove, the charges or forces are contained within the layer 3, as distinguished from being on the surface thereof, whereby the charges in areas 6' are not discharged by accidental contact with the outer surface of the layer 3.

Disposed adjacent to the exposure station 50 and spaced therefrom in the direction of travel of the recording member 1 is a development station 70 at which is provided a heat source such as the bulb 72 which is a source of infrared radiation, the bulb 72 being supported by a standard 71 and having a pair of electrical input terminals 73 and 74, the terminal 73 being connected to the neutral conductor N and the terminal 74 being connected through a switch 47 and the conductor 48 to the line conductor 41. Upon closure of the switch 47, the bulb 72 radiates infrared energy which is directed toward the upper surface of the recording member 1, which energy heats the upper layer 3 to the plastic state thereof whereby to permit the charges or forces in the area 6' to deform the thermoplastic resin in the layer 3. It will be understood that the heat derived from the source 72 is not sufficient to raise the temperature of the support 2 to the plastic state thereof.

Disposed adjacent to the developing station 70 and spaced therefrom in the direction of travel of the recording member 1 is a cooling station 80 at which is disposed upon a standard 81 a drive motor '82 having an output shaft 83 carrying a fan blade 84 on the lower end thereof. The motor 82 further has electrical input terminals 85 and 86, the input terminal 85 being connected to the neutral conductor N and the input terminal 86 being connected through a conductor 87 and a switch 49 to the line conductor 41. Upon closure of the switch 49, the motor 82 operates to cause the fan blade 84 to direct a stream of cooling air upon the layer 3 of the recording member 1, thereby to cool the layer 3 to the solid condition so as to preserve the deformations in the upper surface thereof. There is illustrated in FIG. 7 of the drawings an enlarged view of the deformations 8 formed in the upper surface of the layer 3, the original outer surface 9 having been slightly raised due to the displacement of material from the deformations 8, the bases 10 of the deformations 8- being substantially on a common plane since the exposures forming the deformations 8 were all substantially uniform, it being understood that the depth of the deformation 8 and hence the position of the bases 10 is a function of the exposure of the layer 3 to the activating radiation. Each of the deformations 8 is further defined by a pair of outwardly and upwardly diverging walls 1 interconnecting the upper surface 9 and the bases 10. It is the inclined side walls 11 which deflect light in a schlieren projection system so that the presence of deformations 8 can be optically detected and the information represented thereby projected by the schlieren projection system.

Other flexible transparent substrates or supports 2 may be used that are formed of flexible synthetic organic polymers, which polymers may be thermoplastic provided that the temperature at which the thermoplastic polymers reach the plastic state is substantially above the temperature at which the thermoplastic in the layer 3 reaches the plastic state. The preferred polymers for the support 2 are the heat resistant compositoins, such as aromatic polyesters or polyamides that reach a plastic condition above 150 C. or higher, (as for instance, those described in the Journal of Polymer Science, vol. 40, pages 289 and 418, November 1959), although the thermoplastic compositions having even higher temperatures for the plastic condition thereof are within the scope of the invention. The support 2 of the recording member 1 is of greater thickness than the layer 3 to impart sufficient mechanical strength to the composite recording member 1 for ordinary handling as well as to provide a heat-sink for cooling the thermoplastic layer 3 after heat development of the information-bearing deformations thereon. If the recording member 1 is to be transparent, it is necessary that the thermoplastic resin of the support 2 be optically clear material. Suitable compositions in addiiton to those mentioned above are acetal polymers, silicone resins, and polycarbonate resins.

10 EXAMPLE 3 There is illustrated in FIG. 9 of the drawings another preferred form of recording member 101 useful in the present invention, the recording member 101 including a support 102, a layer 103 of dielectric material containing a photosensitive substance and an electrically conductive film 112 which is disposed between the support 102 and the layer 103. The support 102 is a commercially available transparent polyethylene terephthalate resin having a thickness of 50 microns. The film 112 is formed of cuprous iodide and has a thickness of about 0.005 micron. The outer layer 103 is formed of polystyrene having iodoform distributed therein and made in accordance with Example 1 above and having a thickness of about 15 microns. As illustrated, the conductive film 112 completely covers the upper surface of the support 102, but the side edges of the layer 103 are set back from the edges of the support 102 and the film 112, whereby to leave an exposed upper surface 113 of the film 112 on each side of the layer 103.

The cuprous iodide conductive film is formed by vacuum depositing a thin film of metallic copper on the upper surface of the support 102, and then exposing the metallic copper to iodine vapor to form a conductive cuprous iodide film. For a more detailed description of a suitable method and apparatus for producing a transparent conductive cuprous iodide film, reference is made to US. Pat. No. 2,756,164, granted July 24, 1956 to D. A. Lyon and entitled Electrically Conducting Films and Processes for Forming the Same. Other conductive films may be utilized in the place of the cuprous iodide film described above, suitable materials including metals such as chromium, iron, and nickel, and metal oxides such as indium oxide.

As illustrated, the recording members 101 in FIGS. 8 to 11 are shown as individual blocks roughly rectangular in shape. However, it is contemplated that the recording member 101 can be in a continuous strip or tape, in which case the recording member 101 must have the necessary flexibility to allow winding thereof around small diameter mandrels, for example /1; inch diameter mandrels, which is the usual requirement for conventional projection machines. In such a construction, as well as the construction illustrated in FIGS. 8 to 11, the support 2 has a thickness in the range from about 25 microns to about microns, the electrically conductive film 112 has a thickness in the range from about 0.001 micron to about 0.01 micron and the layer 103 has a thickness in the range from about 5 microns to about 50 microns. As has been explained heretofore, it is advisable that the thermoplastic layer 103 have a thickness no less than 5 microns in order to obtain a well-defined deformation image; however, if the thickness of the layer 101 exceeds 50 microns, there is a tendency of the layer 101 to retain solvent.

There is illustrated in FIG. 8 of the drawings a system particularly adapted for exposing and developing the recording member 101 of Example 3 above. The system 120 includes a base 121 having an upstanding support 122 at the lefthand end thereof and carrying at the upper end thereof a shaft 123 for supporting a pulley 124. The base 121 also has a second upstanding support 125 at the righthand end thereof and carrying at the upper end thereof a shaft 126 for supporting a pulley 127. The pulleys 124 and 127 cooperate to support and guide a continuous belt 129, the pulley 127 being provided with a drive pulley 128 so that the pulley 127 can be driven by a drive motor and in turn drive the belt 129, the direction of movement of the pulleys 124 and 127 being in a clockwise direction, whereby the upper reach of the belt 129 moves to the right in FIG. 8. The drive motor 130 is also mounted upon the base 121 and has an output shaft 131 carrying a drive pulley 132, a flexible belt 133 interconnecting the drive pulleys 128 and 132, whereby the drive motor 130 can drive the pulley 127 as illustrated. Power for operation of the motor 130 is derived from a commercial 236 volt, 60 cycle A-C Edison supply designated by the numeral 140 and including a terminal board B carrying connections for the outer power conductors L1 and L2 that are connected respectively to line conductors 141 and 142 and carrying a connection for the inner neutral conductor N that is grounded. The motor 130 has a pair of output terminals 134 and 135, the terminal 134 being connected to the line conductor 141 and the terminal 135 being connected to the line conductor 142 via a control switch 143 and a conductor 144.

The recording members 101 in the system 120 are fed onto the conveyer belt 129 from a chute 136' supported by a standard 137 mounted on the base 121, the lower end of the chute 136 delivering the recording members 101 onto the upper surface of the upper reach of the conveyer belt 129 substantially above the pulley 124. Disposed adjacent to the pulley 127 is a receptacle 138 mounted on the base 121 and in position to receive the processed recording members 101 from the conveyer belt 129.

The system 120 also includes an exposure station 150 at which there is provided a standard 151 that holds a support 152 overlying a section of the support belt 129, the support 152 being adapted to hold in operative position above a section of the belt 129 a photographic negative 104. Disposed above the support 152 and spaced therefrom is a source of activating radiation in the form of a light bulb 153 of the tungsten filament type mounted upon a standard 154, the bulb 153 being provided with the usual socket having a pair of electrical input terminals 155 and 156, the terminal 155 being connected to the neutral conductor N and the terminal 156 being connected to the line conductor 141 through a control switch 145 and a conductor 146. The light bulb 153 emits essentially white light, and it will be understood that the photographic negative 104 has portions 106 thereof (see FIG. 9) that are transparent to the activating radiation or light (designated by the numeral 157 in FIG. 9) from the light bulb 153, and further the support 152 is transparent to the activating radiation 157 from the light bulb 153, and is preferably formed of glass. As is illustrated in FIG. 9, the photographic negative 104 has portions opaque to the light 157 and disposed between the portions 106 that are transparent to the light 157, the transparent portions 106 transmitting the light 157 which is directed thereupon onto certain predetermined areas of the upper surface of the layer 103 and in point-by-point correspondence to the transparent portions 106 in the photographic negative 104. It will be understood that the length of the exposure of the recording member 101 to the activating radiation 157 through the photographic negative 104 is determined by the length of time that the switch 145 is closed. After exposure at the station 150, there are thought to be present within the upper layer 103 a plurality of pairs of charges in the areas or zones 106 corresponding to the areas struck by the activating radiation 157, as shown in FIG. 10. As has been pointed out hereinabove, the charges are contained within the layer 103, as distinguished from being on the surface thereof, whereby the charges in the areas 106 are not discharged by accidental contact with the outer surface of the layer 103.

Disposed adjacent to the exposure station 150 and spaced therefrom in the direction of travel of the recording members 101 is a developer 170 for developing the force pattern in the recording member 101 into a visual image in the nature of deformations on the upper surface thereof. The developer 170 is supported by standards 171 mounted on the base 121, the developer 170 being electrically operated, whereby a pair of electrical input terminals 172 and 173 is provided, the terminal 172 being connected to the neutral conductor N and the input terminal 173 being connected via a switch 147 and a conductor 148 to the line conductor 141. The output from the developer 170 appears at a pair of output terminals 174 and 175 that are connected respectively by conductors 176 and 177 to a pair of spring contacts 178 and 179 (see FIG. 10 also). As may be best seen in FIG. 10, the spring contacts 178 and 179 make firm mechanical and electrical contact with the conductive film 112 at the exposed upper surfaces 113 on each side of the recording member 101, whereby any potential applied between the spring contacts 178 and 179 is applied across and through the conductive filament 112. The developer serves to provide a measured pulse of AC current at a predetermined voltage so as to deliver a desired amount of current to the conductive film 112 which when applied to the conductive film 112 develops heat therein due to the resistance thereof. The heat produced in the conductive film 112 is applied to the contacting layers including the upper layer 103 to cause heating thereof, the amount of heat delivered being calculated to be such that the layer 103 is raised to a temperature such that the thermoplastic resin therein is in the plastic condition for a suitable period of time so that the force pattern therein can deform the upper surface thereof.

Disposed adjacent to the developer 170 and spaced therefrom in the direction of travel of the conveyor belt 129 is a cooling station 180 at which is disposed upon a standard 181 a drive motor 182 having an output shaft 183 carrying a fan blade 184 at the lower end thereof. The motor 182 has electrical input terminals 185 and 186, the input terminal 185 being connected to the neutral conductor N and the input terminal 186 being connected through a conductor 187 and a switch 149 to the line conductor 141. Upon closure of the switch 149, the motor 182 operates to cause the fan blade 184 to direct a stream of cooling air upon the layer 103 of the recording member 101, thereby to cool the layer 103 to the solid condition so as to preserve the deformations in the upper surface thereof.

There is illustrated in FIG. 11 of the drawings an enlanrged view of the deformations 108 formed in the upper surface of the layer 103, the original outer surface 109 having been slightly raised due to the displacement of material from the deformations 108, the bases 110 of the deformations 108 being substantially on a common plane since the exposures forming the deformations 108 were all substantially uniform, it being understood that the depth of the deformations 108 and hence the position of the bases 110 is a function of the exposure of the layer 103 to the activating radiation. Each of the deformations 108 is further defined by a pair of upwardly and outwardly diverging side walls 111 interconnecting the upper surface 109 and the bases 110. It is the inclined side walls 111 which deflect light in the schlieren projection system so that the presence of the deformations 108 can be optically detected and the information represented thereby projected by the schlieren projection system.

Other photosensitive substances may be used in the present invention in place of the iodoform illustrated in Examples 1 to 3 above. A large number of halogenated hydrocarbons, and particularly polyhalogenated hydrocarbons are useful, the preferred compounds being those in which the carbon atom to which the halogen is attached has no more than two hydrogen atoms attached thereto, and preferably only one hydrogen atom attached thereto, thereby to render the compound more readily ionizable. Also the higher halogens, i.e., chlorine, bromine and iodine are preferred. The following is an example of another short chain aliphatic polyhalogenated hydrocarbon useful as a photosensitive substance in the present 1nvent1on.

In the following specific working examples of the inventron, Examples 4 through 43 all discloses recording members 101 embodying thermoplastic layers 103 contaming photosensitive substances cast upon a transparent electrically conductive film 112 of cuprous iodide approximately 0.005 micron in thickness formed upon one surface of a glass support 102 similar to a microscope slide, all as described in Example 3. In each case, the exposed and developed recording member 101 was placed in a schlieren projector and it was found that the deformation image developed thereupon had a point-to-point correspondence to the original image pattern to Which each had been exposed.

EXAMPLE 4 A recording member like the recording member 101 of Example 3 was formed by casting upon the outer surface of the film 112 a thermoplastic layer 103 having a thicknecs of 25 microns and formed a polystyrene of the type set forth above with respect to Example 1 and having incorporated therein 7.5 percent by weight of methylene iodide in place of the iodoform of Example 1.

The recording member 101 made in accordance with Example 4 was processed in the system 120 of FIG. 8, and during the processing thereof was first exposed at the exposure station 150 through a photographic negative of a 500 mesh screen at 500 watts for two minutes. Thereafter the exposed recording member 101 was developed by heating at the developing station 170 by applying 500 watts of electricity through the film 112 for 0.3 second.

The following is an example of yet another short chain aliphatic polyhalogenated hydrocarbon useful as a photosensitive substance in the present invention.

EXAMPLE 5 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 1.75 Benzene 4.55 Toluene 0.70 Tetraiodoethylene 0.09

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having disposed therein about 5 percent by weight of tetraiodoethyelene, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 5 was processed in the system 120, and during the processing was exposed to 500 watts illumination for three minutes through a photographic negative at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

Other classes of compounds are useful as photosensitive substances in the layers 3 and 103 of the recording members 1 and 101, respectively, in place of the halogenated hydrocarbons utilized in Examples 1 to 5 above. More specifically, it has been found that the benzoquinones are useful, the following being an example .thereof.

EXAMPLE 6 A coating solution for forming the layer 103 was prepared having the following composition:

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having disposed therein about 5 percent by weight of p-benzoquinone, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 6 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 1 minute through a photographic negative at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

The following is an example of a compound useful as a photosensitive substance which is both a polyhalogenated hydrocarbon and a benzoquinone.

14 EXAMPLE 7 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 1.75 Benzene 4.55 Toluene 0.70

Chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone) 0.07

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having disposed therein about 4 percent by weight of chloranil, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 7 was processed in the system 120, and during the processing was exposed to 500 watts illumination for thirty seconds through a photographic negative at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

Other recording members 101 were made in accordance with Example 7 but utilizing successively smaller concentrations of chloranil in the layer 103, and it Was found that perfectly satisfactory recording members could be formed utilizing a chloranil content in the layer 103 of 2 percent, 1 percent, and 0.5 percent by weight.

The following is yet another example of a benzoquinone compound useful as a photosensitive substance in the present invention.

EXAMPLE 8 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 2.1 Benzene 4.2 Xylene 0.7- Phenyl-p-benzoquinone 0 .02

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having disposed therein about 1 percent by weight of phenyl-pbenzoquinone, the layer 103 having a thickness of 25 microns and being pale green in color.

The recording member 101 of Example 8 was processed in the system and during the processing was exposed at the exposure station to 500 watts illumination for fifteen seconds through a photographic negative and a 500 mesh screen, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

Yet another example of a class of compounds useful as photosensitive substances in the present invention are nitrophenylamines. The following are examples of such compounds utilized in the present invention as photosensitive substances.

EXAMPLE 9 A coating solution for forming the layer 103 was prepared having the following composition:

. Grams Polystyrene resin solids (like Example 1) 1.75 Benzene 4.55 Toluene 0.70 m-Nitroaniline (l-amino-B-nitrobenzene) 0.02

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having disposed therein about 1 percent by weight of m-nitroaniline, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 9 was processed in the system 120, and during the processing was exposed to 500 watts illumination for one minute through a photographic negative at the exposure station 150, and was 1 5 thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

EXAMPLE A coating solution for forming the layer 103 was prepared having the following composition:

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 1 percent by weight of 2- nitrodiphenylamine, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 10 was processed in the system 120, and during the procesing was exposed to 500 watts illumination for 30 seconds through a photographic negative at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

Still another example of a class of compounds useful as photosensitive substances in the present invention are the (arylazo)aryl compounds. The following are examples of such compounds utilized in the present invention as photosensitive substances.

EXAMPLE 11 A coating solution for forming the layer 103 was prepared having the following composition:

The coating solution was cast upon the conductive film 112 and the solvents removed by heat. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 1 percent by weight of azobenzene, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 11 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 30 seconds through a photographic negative at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

A particular useful group of compounds from the class of (arylazo)aryl compounds are the (arylazo) arylamines. The following are examples of such compounds utilized in the present invention as photosensitive substances.

EXAMPLE 12 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 1.75 Benzene 4.55 Toluene 0.70 p-(phenylazo)aniline 0.02

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a yellow thermoplastic layer 103 of polystyrene resin having incorporated therein about 1 percent by weight of p-(phenylazo) aniline, the layer 103 having a thickness of 20 microns.

The recording member of Example 12 was processed in the system 120 and during the processing was exposed to 500 watts illumination for 5 seconds through a photographic negative at the exposure station 150, and was thereafter developed by applying 500 Watts of electrical energy for 0.06 second at the developer 170.

16 The (arylazo) arylamine may be N-substituted and still be useful as a photosensitive substance in the present invention, the following being examples of such compounds.

EXAMPLE 13 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 1.75 Benzene 4.55 Toluene 0.70 N,N-dimethyl-p-(phenylazo)aniline 0.02

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a yellow-orange thermoplastic layer 103 of polystyrene resin having incorporated therein about 1 percent by Weight of N,N-dimethyl-p-(phenylazo)aniline, the layer 103 having a thickness of 15 microns.

The recording member 101 of Example 13 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 10 seconds through a photographic negative at the exposure station and was thereafter developed by applying 500 watts of electrical energy for 0.05 second at the devolper during the exposure, the color of the layer 103 changed from a yellow-orange color to a brown color.

In a subsequent processing of a recording member 101 made in accordance with Example 13, the exposure was for only 5 seconds rather than 10 seconds, a good reproduction of the subject matter on the photographic negative being obtained with only 5 seconds exposure. Yet another recordingmember 101 made in accordance with Example 13 was first exposed to ordinary room light for 24 hours before processing through the system 120; this recording member 101 was then processed as described above with respect to Example 13 and again a good reproduction of the subject matter on the photographic negative was obtained on the surface of the layer 103, this demonstrating that there is no loss in sensitivity with exposure to roomlight for an extended period of time. The recording member 101 processed as in Example 13 above was subsequently'erased by applying 500 watts of electrical energy for 0.3 second, and after the application of the erasing energy, not only were the deformations gone from the surface of the layer 103, but the color of the layer 103 had changed from brown to the original yelloworange color thereof.

EXAMPLE 14 EXAMPLE 15 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 2.1 Benzene 4.2 Xylene 0.7 4-(phenylazo)diphenylamine 0.07

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein 3.3 percent by weight of 4-(phenylazo)diphenylamine, the layer 103 having a thickness of 15 microns and being light yellow in color.

The recording member 101 of Example 15 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 7 seconds through a photographic negative and a 750 mesh screen at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

It further was found that the recording member 101 made in accordance with Example 15 could be erased by applying 500 watts of electrical energy for 0.4 second, all of the deformations on the surface of the layer 103 being obliterated by the erasing procedure. It further was found that the recording member 101 of Example 15 could 'be exposed for a shorter period of time, namely seconds, and still produce a good reproduction of the subject matter on the photographic negative on the surface of the layer 103 in the form of deformations therein.

EXAMPLE 16 The procedure of Example was repeated to produce a recording member 101 having in the layer 103 as a photosensitive substance about 3 percent by weight of N-(p-methoxybenzylidene)-p-(phenylazo)aniline. The resultant recording member gave a good picture when exposed and developed as set forth in Example 15 above.

It has been found in general that in the (arylazo)aryl compounds useful as photosensitive substances in the present invention, the arylazo group may be a benzylazo group and in Examples 11 to 16 above, may be ring substituted benzylazo groups may be a naphthylazo group or may be, ring substituted naphthylazo groups. Further the aryl group, such as in the arylamine group, may be a benzyl group, a ring substituted benzyl group, a naphthyl group, or a ring substituted naphthyl group. The following is an example of a photosensitive substance wherein the arylazo group is a ring substituted benzylazo group and the arylamine group is a ring substituted benzylamine group.

EXAMPLE 17 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids, (like Example 1) 1.75 Benzene 4.55 Toluene 0.70

4-(3,5-dimethyl-4-phenylazo) 3,5 dimethylaniline hydrochloride 0.07

The photosensitive substance was slightly unsoluble in the solvents, and accordingly, the coating solution was first filtered. Thereafter the coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein approximately 3 percent by weight of 4-(3,5-dimethyl-4-phenylazo)-3,5- dimethylaniline hydrochloride, the layer 103 having a thickness of microns.

The recording member 101 of Example 17 was processed in the system 120, and during the processing was exposed to 500' watts illumination for 5 seconds through a photographic negative and a 500 mesh screen at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

EXAMPLE 18 A coating solution for forming the layer 103 was prepared having the following composition:

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 3.3 percent by weight of 2- methoxy-4-(o-methoxyphenylazo) aniline, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 18 was processed in the system 120, and during the processing was exposed to 500 watts of illumination for 5 seconds through a photographic negative and a 500 mesh screen at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

EXAMPLE 19 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 2.1 Benzene 4.2 Xylene 0.7 N,N'-dimethyl-p-(m-tolylazo) aniline 0.07

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 3.3 percent by weight of N,N- dimethyl-p-(m-tolylazo)aniline, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 19 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 5 seconds through a photographic negative and a 500 mesh screen at the exposure station 150, and was thereafter developed by supplying 500 watts of electrical energy for 0.1 second at the developer 170.

EXAMPLE 20 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 2.1 Benzene 4.2 Xylene 0.7 4,4'-azobis(N,N-dimethylaniline) 0.07

The photosensitive substances had a low solubility in the solvents, and accordingly, the coating solution was first filtered to remove the insoluble matter therein. The coating solution was then cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein approximately 1 percent by weight of 4,4-azobis(N,N'-dirnethylaniline), the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 20 was processed in the system and during the processing was exposed to 500 watts illumination for 7 seconds through a photographic negative and a 750 mesh screen at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

The following is an example of the use of a photosensitive substance in the present invention of the (arylazo) arylamine type wherein the arylazo group is a naphthylazo group and the arylamine is a diamine.

EXAMPLE 21 A coating solution forming the layer 103 was prepared having the following composition:

' Grams Polystyrene resin solids (like Example 1) 2.1 Benzene 4.2 Xylene 0.7

Fat Brown RR [4 (naphthylazo) m phenylenediamine] 0.07

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 3.3 percent by weight of Pat Brown RR, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 21 was processed in the system 120, and during the processing was exposed to 500 watts illumination for seconds through a photographic negative at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.01 second at the developer 170.

EXAMPLE 22 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 2.1 Benzene 4.2

Xylene 0.7 N,N'-dimethyl-p-(l-naphthylazo)aniline 0.07

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 3.3 percent by weight of N,N- dimethyl-p-(l-naphthylazo)aniline, the layer 103 having a thickness of microns and being a dark orange color.

The recording member 101 of Example 22 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 7 seconds through a photographic negative and a 750 mesh screen at the exposure station 150 and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170; the color of the layer 103 darkened slightly during exposure.

EXAMPLE 23 A recording member 101 was made as in Example 22 above but there was substituted for the photosensitive substance thereof an equal amount of N,N-dimethyl-p- (2-naphthylazo)aniline. The resultant layer 103 was yellow in color and upon exposure as in Example 22 above turned brown in color. The subject matter on the photographic negative was faithfully reproduced on the recording member 101 and specifically on the surface of the layer 103 in the form of deformations therein upon thermal development.

The following is an example of a photosensitive substance useful in the present invention of the class comprising (arylazo)aryl compounds, wherein the arylazo group is a ring substituted naphthylazo and the aryl group is a ring substituted benzyl group.

EXAMPLE 24 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 2.1 Benzene 4.2 Xylene 0.7 Oil Scarlet-6G [1-(2,4-xylylazo)-2-naphthol] 0.07

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 3.3 percent by weight of Oil Scarlet-6G, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 24 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 5 seconds through a photographic negative at the exposure station 150, and was thereafter developed by supplying 500 watts of electrical energy for 0.1 second at the developer 170.

The following is an example of photosensitive substances useful in the present invention from the class comprising (arylazo)arylamines, wherein the arylamine is a naphthylamine.

EXAMPLE 25 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 2.7 Benzene 4.2 Xylene 0.7 '4-(phenylazo)-l-naphthylamine a 0.0

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted 'a thermoplastic layer 103 of polystyrene resin having in- 'corporated therein about 3.3 percent by weight of 4- (phenylazo)-1-naphthylamine, the layer 103 having a thickness of 18 microns and being orange in color.

The recording member 101 of Example 25 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 7 seconds through a photographic negative and a 750 mesh screen at the exposure station 150, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second at the developer 170.

Another class of compounds useful as photosensitive substances in the present invention are arylazo (arylazo) aryl compounds, wherein the first arylazo group may be a benzylazo group, a ring substituted benzylazo group, a naphthyl group, or a ring substituted naphthylazo group; and the second (arylazo) group may be a benzylazo group, a ring substituted benzylazo group, a naphthylazo group, or a ring substituted naphthylazo group; and the aryl group may be a benzyl group, a ring substituted benzyl group, a naphthyl group, or a ring substituted naphthyl group. The following is an example of a photosensitive compound of this class which is a ring substituted benzylazo(benzylazo) ring substituted naphthyl compound.

EXAMPLE 26 A coating solution for forming the layer 103 was prepared having the following composition:

' Grams Polystyrene resin solids (like Example 1) 2.1 Benzene 4.2 Xylene 0.7

Sudan Red BBA (also known as Oil Red 7B) [1-(4- o-tolylazo-o-tolylazo)-2-naphthol] 0.07

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 3.3 percent by weight of Sudan Red BBA, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 26 was processed in the system 120, and during the processing was exposed to 500 watts illumination for 5 seconds through the photographic negative at the exposure station 150, and thereafter developed by supplying 500 watts of electrical energy for 0.1 second at the developer 170.

EXAMPLE 27 A recording member 101 was made in accordance with Example 26 above but substituting Oil Red 0 [l-(xylylazo-p-xylylazo)-2-naphthol] for the Sudan Red BBA, the Oil Red 0 being utilized in a quantity to provide about 3.3 percent by weight thereof in the layer 103. The resultant recording member 101 was useful in the system in the same manner as the recording member 101 of Example 26.

EXAMPLE 28 A recording member 101 was made in accordance with 21 Example 26 above but substituting Sudan Black B having the structural formula:

for the Sudan Red BBA, the Sudan Black B being utilized in an amount to provide about 1 percent by weight thereof in the layer 103. The resultant recording member 101 was useful in the system 120 in the same manner as the recording member 101 in Example 26.

In each of Examples 1 through 29 above, a single photosensitive substance has been utilized in the layer 3 or 103, as the case may be, of the recording member. It has been found that highly beneficial and synergistic results can be obtained by incorporating more than one of the photosensitive substances in the layer 3 or 103. The following examples of recording members incorporating more than one photosensitive substance in the recording layer thereof.

EXAMPLE 29 A coating solution for the layer 103 was prepared having the following composition:

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein 7.6 percent by weight of iodoform and 1.5 percent by weight of chloranil, the layer 103 having a thickness of 25 microns and being light yellow in color.

The recording member 101 of Example 29 was processed in the system 120, and during the processing was exposed at the exposure station 150 to 500 watts illumination for 7 seconds through a photographic negative, and was thereafter developed at the developer 170 by applying 500 watts of electrical energy for 0.1 second.

EXAMPLE 30 A coating solution for forming the layer 103 was prepared having the following composition:

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 2.0 percent by weight of p- (phenylazo)-aniline and about 2.0 percent by weight of N,N'-dimethyl-p-(phenylazo) aniline, the layer 103 having a thickness of 20 microns and being yellow in color.

The recording member 101 of Example 30 was processed in the system 120, and during the processing was exposed at the exposure station 150 to 500 watts illumination for 3 seconds through a photographic negative, and was thereafter developed at the developer 170 by applying 500 watts of electrical energy for 0.05 second. Further, it was found that the thermoplastic layer 103 was substantially more sensitive to light than a layer containing only 4 percent by weight of p-(phenylazo)aniline or a layer 103 containing only 4 percent by weight of N,N-dimethyl-p- (phenylazo aniline.

As is illustrated by Examples 1 to 30 above, a wide variety of photosensitive substances are useful in the present invention. Preferably the photosensitive substance is soluble in the thermoplastic layer 3 or 103, as distinguished from being merely physically dispersed therein, since the recording member 101 is capable of far greater resolution when the photosensitive substance is soluble in the thermoplastic layer 103; however, recording members wherein the photosensitive substance is merely physically dispersed in the dielectric material are also useful.

The photosensitive substances illustrated above when incorporated in a suitable dielectric material are thought to produce electrical forces therein in response to exposure thereof to activating radiation therefor, i.e., there are generated in the dielectric material electrical pairs, such as, a positive ion and a negative ion, a positive ion and an electron, or a negative ion and a hole; it is believed that there is the production of such electrical pairs, as distinguished from the production of free radicals, by the photosensitive substances when activated thus producing substantially equal numbers of positive and negative charges, thereby not disturbing the over-all electrical neutrality of the dielectric material after exposure to the activating radiation.

It further has been observed that the recording members utilizing polyhalogenated hydrocarbons and the photosensitive substance therein possess another important characteristic not possessed by the recording members utilizing other photosensitive substances. More specifically, it has been found that many recording members exhibit the phenomena of memory, particularly those which utilize iodoform, methylene iodide, and tetraiodoethylene as photosensitive substances, i.e., an image produced thereon by exposure and development, and present in the form of deformations on one surface thereof, can be erased by heating, and after erasing can be produced thereon again by a second developing step without further exposure. The phenomenon of memory is particularly noticeable when the recording member is over exposed to the activating radiation, i.e., when the amount of radiation utilized is substantially greater than that necessary to form a discernible reproduction of the information in the surface of the recording member. For example, when the recording member 1 of Example 1 is exposed to a 500 watt source for one minute, it is found that the recording member 1 is overexposed, but nonetheless a suitable image of the subject matter to be reproduced is formed on the surface of the layer 3 by heating at 500 watts for 0.1 second. The deformations on the surface of the layer 3 can be destroyed or obliterated by thereafter heating with 500 watts of electrical energy for 0.3 second. If after erasure, the recording member 1 is cooled to room temperature, the original deformations can be redeveloped therein using 500 watts of electrical energy applied for 0.1 second, all without additional exposure. It will be noted that the energy required for erasure is substantially greater than that required for development, approximately three times as much energy being required for erasure as that required in the development for the example given. It has been found that the recording member 1 of Example 1 can be erased and redeveloped without reexposure as many as five times or more and still produce a discernible reproduc tion of the subject matter in the surface of the layer 3.

An important advantage of the memory characteristic of the recording members made in accordance with Examples 1 to 5 resides in the fact that any inadvertent damage to the surface of the layer 3 may be repaired without loss of the subject matter recorded thereon. For ex ample, during certain contact print out processes such as have been described above, random static charges on the contacting surface of the sheet being copied tend to be transferred to the recording member 1 and to be reproduced along with the copied image. If the recording member 1 is thereafter erased in the manner above described, and the development step repeated, the subject matter sought to be reproduced is restored to the layer 3 in the form of deformations therein free of the unwanted deformations caused by the random static charges transferred.

The memory in the recording member after the original exposure and development can be readily destroyed by flooding the surface of the recording member with activating radiation followed by heating or by heating for extended periods of time. In general, the persistence of the memory effect increases with the exposure time at constant intensity, or increases with constant exposure time at an increasing intensity. It will be seen therefore that if desired a portion of the surface of a recording member can be erased by exposure to uniform activating radiation followed by heating, and the selected area thereafter re-exposed, in this manner the information on a recording member can be updated, corrected and changed without the necessity of re-exposing and redeveloping the entire surface of the recording member.

It further has been found that the quality of the reproductions of information on the recording members 1 and 101 and the speed and ease with which the reproductions can be made, i.e., the length of the exposure and development cycles, can be modified by incorporating therein light sensitizers that serve to decrease the exposure period and spectral response broadeners which broaden the region of spectral response to activating radiation, all of which materials are hereinafter referred to as sensitizing agents. A wide variety of materials are useful as sensitizing agents, the better sensitizing agents being complexing amine. The following are examples of the use of various sensitizing agents together with photosensitive substances.

EXAMPLE 31 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 1.75 Benzene 4.55 Toluene 0.70 Iodoform 0.044 Diphenylamine 0.009

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 2.5 percent by weight iodoform and 0.5 percent by weight of diphenylamine, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 31 was processed in the system 120, and during the processing Was exposed at the exposure station 150 to 500 watts illumination for seconds through a 500 mesh screen, and was thereafter developed at the developer 170 by applying 500 watts of electrical energy for 0.1 second.

EXAMPLE 32 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 1.75

Benzene 4.55

Toluene 0.70

Chloranil 0.07 DMP-30 [2,4,6 tris (dimethylaminomethyl)phenol] 0.035

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There results a thermoplastic layer 103 of polystyrene resin having incorporated therein about 4 percent by weight chloranil and about 2 percent by weight of DMP-30, the layer 103 having a thickness of 25 microns and being purplish brown in color.

24 The recording member 101 of Example 32 was processed in the system 120, and during the processing was exposed at the exposure station to 500 watts illumination for 15 seconds through a photographic negative and was thereafter developed at the developer by applying 500 watts of electrical energy for 0.1 second. It further was found that the deformations were sharper and deeper for a like exposure time as compared to recording members 101 made like Example 32 but containing only the chloranil, i.e., not including the sensitizing agent DMP-30, and further that the recording member 101 of Example 32 gave upon a shorter time of exposure a reproduction of the subject matter of the photographic negative that was equal in quality to that obtained using a longer time of exposure applied to recording members having only chloranil therein.

EXAMPLE 3 3 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 1.75 Benzene 4.5 5

Toluene 4 0.07 p-(Phenylazo)aniline DMP-30 0.07

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 4 percent by weight of p-(phenylazo)analine and about 4 percent by weight of DMP-30 (sensitizing agent), the layer 103 having a thickness of 20 microns.

It also has been found that the recording members 101 that include a sensitizing agent, such as the recording members 101 of Examples 31, 32, and 33 above exhibit the phenomenon of memory, i.e., an image produced thereon by exposure and development and present in the form of deformations in one surface thereof can be erased, and after erasure can be produced thereon again by a second developing step without further exposure. For example, the recording member 101 of Example 31 utilizing iodoform as the photosensitive substance and diphenylamine as the sensitizing agent was exposed and developed as described in Example 31 to transfer the subject matter on the photographic negative to the surface of the layer 103 in the form of deformations therein. The deformations were thereafter erased by applying by means of the developer 170, 500 watts of electrical energy for 0.3 second, i.e., approximately three times the energy utilized initially to develop the recording member 101. This erasing step appeared to destroy the deformations on the surface of the layer 103 corresponding to the subject matter on the photographic negative. Thereafter the recording member 101, without further exposure at the exposure station 150, was developed for a second time at the developer 170 by applying 500 watts of electrical energy for 0.1 second, that is, an amount of energy equal to the original development energy and approximately one-third of that utilized to erase the deformations in the layer 103. The original deformations were again produced on the surface of the layer 103, the deformations corresponding point-by-point to the subject matter on the photographic negative and to the subject matter on the recording member 101 as originally developed. It was found in fact that the recording member 101 of Example 31 could be erased and redeveloped as many as five times or more and still produce a recognizable reproduction of the subject matter on the photographic negative on the surface of the layer 103 in the form of deformations therein. The recording member 101 of Example 31 further was found to exhibit a more persistent memory effect than such a recording member formed using only iodoform as the photosensitive substance.

The following are examples of recording members 101 utilizing iodoform as a photosensitive substance and illustrating other sensitizing agents therefor.

EXAMPLE 34 A recording member 101 was made in accordance with Example 31 above, but 0.009 gram of triphenylamine was substituted for the diphenylamine in the coating solution, whereby the thermoplastic layer 103 of polystyrene resin had incorporated therein about 2.5 percent by weight iodoform and 0.5 percent by weight of triphenylamine. The resultant recording member 101 when exposed and developed as in Example 31 produced a good reproduction of the subject matter on the photographic negative upon the surface of the layer 103 in the form of deformations therein, and the recording member 101 also exhibited the memory effect, i.e., the deformations on the surface of the layer 103 could be erased and redeveloped without re-exposure.

EXAMPLE 35 A recording member 101 was made in accordance with Example 31 above, but 0.009 gram of dimethylaniline was substituted for the diphenylamine in the coating solution, whereby the thermoplastic layer 103 of polystyrene resin had incorporated therein about 2.5 percent by weight iodoform and 0.5 percent by weight dimethylaniline. The resultant recording member 101 when exposed and developed as in Example 31 produced a good reproduction of the layer 103 in the form of deformations therein, and the recording member 101 also exhibited the memory effect, i.e., the deformations of the surface of the layer 103 could be erased and redeveloped without re-exposure.

EXAMPLE 36 A recording member 101 Was made in accordance with Example 31 above, but 0.009 gram of 1,1-diphenyl- 2-picrylhydrazine was substituted for the diphenylamine in the coating solution, whereby the thermoplastic layer 103 of polystyrene resin had incorporated therein about 2.5 percent by weight iodoform and 0.5 percent by weight of 1,1-diphenyl2-picrylhydrazine. The resultant recording member 101 when exposed and developed as in Example 31 produced a good reproduction of the subject matter on the photographic negative upon the surface of the layer 103 in the form of deformations therein, and the recording member 101 also exhibited the memory effect, i.e., the deformations of the surface of the layer 103 could be erased and redeveloped without re-exposure.

EXAMPLE 37 A recording member 101 was made in accordance with Example 31 above, but 0.009 gram of DMP-30 was substituted for the diphenylamine in the coating solution, whereby the thermoplastic layer 103 of polystyrene resin had incorporated therein about 2.5 percent by weight indoform and 0.5 percent by weight of DMP-30. The resultant recording member 101 when exposed and developed as in Example 31 produced a good reproduction of the subject matter on the photographic negative upon the surface of the layer 103 is the form of deformations therein, and the recording member 101 also exhibited the memory effect, i.e., the deformations of the surface of the layer 103 could be erased and redeveloped without re-exposure.

It further has been found that certain materials which are not photosensitive when utilized alone, i.e., when substituted, for example, in place of iodoform in Example 1 above and exposed to a tungsten filament light source, are rendered photosensitive with respect to tungsten filament light when combined with a sensitizing agent. For example, carbon tetrabromide when substituted for iodoform in Example 1 does not serve as a photosensitive substance when exposed to the tungsten filament light source. However, when carbon tetrabromide is combined with a sensitizing agent such as diphenylamine, DMP30, and the like, the combination of carbon tetrabromide and the sensitizing agent serves as a photosensitive substance. The following are examples of recording members made utilizing this principle.

EXAMPLE 38 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) 1.75 Benzene 4.55

Toluene 0.70 Carbon tetrabromide 0.175 Diphenylamine 0.175

The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 8.35 percent by weight of carbon tetrabromide and about 8.35 percent by weight of diphenylamine, the layer 103 having a thickness of 30 microns.

The recording member 101 of Example 38 was processed in the system 102, and during the processing was exposed at the exposure station to 500 watts illumination for 30 seconds through a photographic negative, and was thereafter developed at the developer by applying 500 watts of electrical energy for 0.1 second. The resultant exposed and developed recording member .101 was placed in a schlieren projector and it was found that the subject matter on the photographic negative was reproduced on the surface of the layer 103 i in the form of deformations therein. If further was found that the deformations could be erased from the surface of the layer 103 by applying 500 watts of electrical energy for 0.3 second, and after cooling to room temperature, the deformations redeveloped therein by applying 500 watts of electrical energy for 0.1 second, all without re-exposure at the exposure station 150.

EXAMPLE 39 A recording member 101 was made in accordance with Example 38 above, but 0.035 gram of DMP-30 was sub stituted for the diphenylamine therein, whereby the thermoplastic layer 103 of polystyrene resin had incorporated therein about 8.9 percent by weight of carbon tetrabromide and about 2 percent by weight of DMP-30. The resultant recording member 101 when exposed and developed as in Example 38 produced a good reproduction of the subject matter on the photographic negative upon the surface of the layer 103 in the form of deformations therein, and the recording member 101 also exhibited the memory effect, i.e., the deformations of the surface of the layer 103 could be erased and redeveloped without re-exposure.

EXAMPLE 40 A recording member 101 was made in accordance with Example 38 above, but 0.14 gram of skatole (3-methylindole) was substituted for the diphenylamine therein, whereby the thermoplastic layer 103 of polystyrene resin had incorporated therein about 8.5 percent by weight of carbon tetrabromide and about 6.8 percent by weight of skatole. The resultant recording member 101 when exposed and developed as in Example 38 but using a 10 minute exposure time, produced a reproduction of the subject matter on the photographic negative upon the surface of the layer 103 in the form of deformations therein, and the recording member 101 also exhibited the memory effect, i.e., the deformations of the surface of the layer 103 could be erased and redeveloped without reexposure. It also was found that the resultant recording member 101 was more sensitive to ultraviolet radiation than to the radiation from the tungsten filament source,

27 whereby exposure to a 100 watt ultraviolet source for minutes followed by development in the usual manner produced a good image of the subject matter on the photographic negative to be reproduced.

EXAMPLE 41 A coating solution for forming the layer 103 was prepared having the following composition:

Grams Polystyrene resin solids (like Example 1) Benzene 65 Xylene 10 Trichloromethyl sulfonylchloride 7 Diphenylamine 2 The coating solution was cast upon the conductive film 112 and the solvents removed by heating. There resulted a thermoplastic layer 103 of polystyrene resin having incorporated therein about 21 percent by weight of trichloromethyl sulfonylchloride and about 6 percent by weight of diphenylamine, the layer 103 having a thickness of 25 microns.

The recording member 101 of Example 41 was processed by exposure to 100 watts of ultraviolet illumination from an AH4 bulb for one minute through a photographic negative, and was thereafter developed by applying 500 watts of electrical energy for 0.1 second.

In Examples 1 to 41 above, the recording layers 3 and 103 are comprised essentially of polystyrene resin as discussed above in detail with respect to Example 1. Other suitable thermoplastic resin compositions that are solid at ambient temperatures may be used for the recording layer in place of the polystyrene illustrated above such as, for example, the Arochlor resins designated Nos. 4465, 5442, and 5460, manufactured by Monsanto Chemical Company, RI-100 resin also manufactured by Monsanto, and Kenfiex A resin manufactured by Kenrich Petrochemicals, Inc. Additional examples of suitable thermoplastic resin compositions are set forth in the Glenn Pat. No. 3,113,179 mentioned above. In general thermoplastic compositions for the solid dielectric recording layers 3 and 103 must be characterized by being in the solid condition at ambient temperatures and up to temperatures of at least 65 C. and by being capable of being converted to the plastic condition by heating to temperatures of 85 C. and above. The thermoplastic compositions in addition must be solvents for or capable of having dispersed therein a photosensitive substance, and must be capable of being selectively deformed in response to the forces of an internal electrical force pattern therein when in the plastic cont dition. The electrical resistivity of the recording layer should be above about 3X10 ohm-centimeters in the liquid state along with a corresponding viscosity of at least about 4,000 centipoises. Other important physical and rheological properties for the recording layer useful in the construction of continuous recording members in tape form include adhesion of the recording layer to the substrate, whether the substrate is a supporting dielectric layer or a conducting layer. Absence of cold flow in the thermoplastic resin composition of the recording layer is also highly desirable in forming solid layers that are to be stored, thereby to prevent any change in the configuration of the recorded information-bearing deformations on the surface thereof, and to prevent sticking between successive layers of the recording member during storage in a rolled configuration. It also is pointed out that the substrate must reach the plastic condition thereof at a temperature substantially higher than that at which the recording layer reaches the plastic condition, 'whereby for example if the recording layer reaches the plastic condition at 85 C., the supporting substrate should reach the plastic condition well above that temperature. It will be understood that if the substrate reaches the plastic condition at higher temperatures, then the recording layer likewise can be of a character which reaches the plastic condition at higher temperatures. Suitable thermoplastic resins having all of the desirable characteristics may be selected from the general class of polymers including acetal resins, acrylic resins, polyester resins, silicone resins and vinyl resins. The following are examples of recording members of the present invention utilizing recording layers made of thermoplastic resins other than the vinyl resins exemplifled in Examples 1 to 41 above.

The following is an example of a recording member wherein the recording layer is a mixture of a diphenyl siloxane resin and a phenylene oxide resin.

EXAMPLE 42 A coating forming the layer 103 having a thickness of 25 microns was cast upon film 112 having the composition:

Parts by weight Polydiphenyl siloxane resin Poly(2,6-dimethyl-1,4-phenylene)ether 10 Iodoform 5 It was found that the layer 103 reached the plastic condition in the temperature range from to C. The recording member 101 of Example 42 was processed in the system 120, and during the processing was exposed at the exposure station to 500* watts illumination for 30 seconds through a photographic negative, and was thereafter developed at the developer by applying 500 watts of electrical energy for 0.1 second.

EXAMPLE 43 A layer 103 having a thickness of 25 microns was applied to conductive film 112 and had the following composition:

Parts by weight Polystyrene resin (like Example 1) 70 n-Terphenyl 2 Butadienestyrene copolymer (95 percent butadiene and 5 percent styrene) 28 Iodoform 5 The recording member 101 of Example 43 was processed in the system 120, and during the processing was exposed at the exposure station 150 to 500 watts illumination for 30 seconds through a photographic negative, and was thereafter developed at the developer 170 by applying 500 watts of electrical energy for 0.1 second.

When forming flexible recording members 1 such as that of Example 2 above, other thermoplastic resins may be used to form the support 2 in the place of the transparent polyethylene terephthalate resin disclosed therein. Other suitable resins for the support 2 may be utilized providing that the temperature of the resin of the support 2 reaches the plastic condition thereof well above the temperature at which the layer 3 reaches the plastic condition thereof. The preferred resins for the support 2 are heat resistant compositions, such as aromatic polyesters and the polyamides which reach the plastic condition above 150 C. or higher (as for instance those described in the Journal of Polymer Science, vol. 40, pages 289, 418, November 1959), and even higher melting point compositions may be utilized. The support 2 is preferably of greater thickness than the recording layer 3 to impart sufficient mechanical strength to the recording member 1 so that it may Withstand ordinary handling as well as to provide a heat sink for cooling the recording layer 3 after heat development of the information-bearing deformations thereof. As has been explained above, in the preferred form of the invention, the entire recording member 1 or 101 is transparent whereby each of the components thereof including the support sheet, the conductive film, if any, and the recording layer must all be optically clear. The resins which possess the necessary optical clarity that are useful for the support 2 are aromatic polyester resins, polyamide resins, acetal resins, silicone resins, polycarbonate resins, and the like.

The conductive film in the case of a transparent recording member must also 'be optically clear so as not to interfere with the faithfulness of the recording process. In addition, the conductive film should exhibit an electrical resistivity which permits resistive or inductive electrical heating of the recording member during the developing process.

In all of the examples given above, two forms of heating have been illustrated for carrying out the development of deformations in the surface of the recording member to form a visual image of the information stored therein, the two forms illustrated being infrared heating as illustrated in FIGS. 1 to 4 and electrical resist ance heating as illustrated in FIG. 8. It Will be understood that other forms of heating may be utilized such as dielectric or induction heating.

Various reflective optical systems are also available which can be utilized to retrieve the information stored as deformations on the surface of a recording member 1 or 101, these reflective optical systems being useful when one or more of the layers forming the recording member are opaque to visible light. More particularly, reflective optical systems having means for projecting a light beam onto the recording layer associated with a lens system for projecting the reflected beam onto' a viewing screen, such systems commonly being termed .light scattering" projection system, may be suitably employed to retrieve the information contained in the surfacefdeformations on the recording member. Alternatively, various known reflective-type schlieren optical systems can be utilized including the device described on page 1970f the Journal of the Optical Society of America (1945) to read out information contained in the surface deformations on a recording member, which recording member may be either transparent or opaque. Such a recording member may utilize an opaque support such as metallic foil or sheet, for example. Retrieval of the information by reflective optical systems has the decided advantage of circumventing any optical discontinuities which may result in faulty retrieval when using transmitted light optical readout systems.

-It is also possible to develop the electrical force pattern within the exposed recording member 101 by means other than deformation of the recording layer'3 or 103 by heating thereof. More particularly, developent systems such as those used in xerography and the like, including charged powders, inks, and dyes, are useful for the production of a visible image on the surface of the recording member of the present invention after exposure to an image pattern. Further details of such development processes are set forth in the co-pending application for United States Letters Patent of Joseph Gaynor and Gordon J. Sewell, Ser. No. 311,160, filed Sept. 24, 1963 for Information Recording and assigned to the assignee of the present invention. It is also" possible to read out the image formed by the electrical force pattern utilizing a photodetector.

EXAMPLE 44 A recording medium was prepared according to Example 1. It was heated to the flow point of the resiniodoform coating under dark room conditions. While in the liquid state, the recording layer wasexposed to an image pattern of white light from a conventional 500 watt projector and the recording medium permitted to cool. The image pattern was maintained until the liquid coating layer solidified. Upon examination in a schlieren projector, the projected image pattern was found to be reproduced in the recording layer. From the foregoing, it will be apparent that an electrical force pattern corresponding to the pattern of the activating radiation was established while the recording layer was in the liquid state and that while it was in the liquid state, surface deformations corresponding to the force pattern were present, which deformations were frozen in upon solidification.

From the foregoing, it will be apparent that recording layers according to this invention which are in the liquid state at room temperature may be employed and be useful in apparatus such as, for example, that disclosed and illustrated in US. Pat. 2,391,451 to Fischer, dated Dec. 25, 1945, utilizing activating radiation in place of the electron beam shown. Of course, other apparatus specifically different from that shown in the patent may also be used.

It is proposed that such a recording medium might be a dielectric organic polymer containing a photosensitive substance and which is liquid at room temperature, or it might be a solution or suspension of a photosensitive substance in an appropriate dielectric organic liquid such as, for example, low molecular weight poly a-methyl styrene, diphenyl oxide, dioctyl phthalate, or the like.

Recapitulating, any liquid dielectric material into which a suitable quantity of the photosensitive substance can be incorporated is useful in the present invention. Likewise any of the photosensitive substances illustrated in Examples 1 to 43 thereof and including the various sensitizing agents illustrated therein may be incorporated in the liquid dielectric materials forming the layer 103, providing that the photosensitive substance and the sensitizing agent, where desired, can 'be incorporated in sufficient quantity into the liquid dielectric material. Likewise the various systems for retrieving the information from the deformations on the surface of the solid layers 103 described above with respect to Examples 1 to 43 may also be utilized to retrieve information from the undulations or modulations in the surface of the liquid layer 103. In this connection it is also noted that a continuous dynamic display of information can be formed on the surface of the layer 103 of any of the Examples 1 to 43 by simply maintaining the layer 103 thereof at a temperature wherein the dielectric material thereof is in the plastic condition, whereby a continuous dynamic display can be projected thereon by a correspondingly modulated activating radiation.

While visible light and ultraviolet light have been utilized as the activating radiation in each of Examples 1 through 44 above, it is to be understood that other forms of activating radiation may be utilized including ultraviolet light, x-rays, gamma rays, and the like, it merely being necessary that the photosensitive substance be reactive to the activating radiation to produce electrical forces in response to exposure thereof to such activating radiation.

From the above it will be seen that there have been provided a recording method and system and recording medium therefor and a record produced thereby which fulfill all of the objects set forth above. More specifically, there has been provided a recording method and system for storing information as a selective electrical force pattern in a dielectric material directly from activating radiation projected onto the surface of the dielectric material in the desired pattern to be recorded, the dielectric material having incorporated therein a photosensitive substance characterized by the production of electrical forces in response to exposure thereof to activating radiation therefor in the selective pattern to be recorded. The dielectric material may be either a liquid whereby to give a dynamic and continually changing display of information if desired, or the dielectric material may be a solid, whereby a permanent record may be made of the information. In the latter case, the dielectric materials preferably are thermoplastic, and upon heating to the plastic condition thereof, the surface thereof is deformed by the electrical force pattern therein to produce a corresponding visible image that is an intaglio reproduction of the information to be recorded. Further, when certain photosensitive substances and/or certain sensitizing agents are utilized, the electrical forces persist in the thermoplastic dielectric material even after repeated heating thereof to the plastic condition and cooling thereof to the solid con- 31 dition, whereby the visible image in the surface of the thermoplastic dielectric material can be alternately erased and developed; in such a method and system, a first electrical force pattern may be established in the dielectric material and thereafter a predetermined area thereof permanently erased by the heating of the dielectric material to the plastic condition thereof and exposing the predetermined area to a uniform pattern of the activating radiation to destroy the electrical force pattern therein, and thereafter the predetermined area can be exposed to a second selective pattern of the activating radiation to produce a corresponding second persistent electrical force pattern therein, whereby to correct and/or update the record.

There further has been provided a recording member which fulfills all of the objects of the invention and that is useful in the recording method and system set forth above, the recording member comprising a layer of dielectric material having incorporated therein a photosensitive substance characterized by the production of electrical forces in response to exposure thereof to activating radiation therefor, there also when desired being incorporated therein sensitizing agents to decrease the exposure from and/or to change or broaden the range of sensitivity to activating radiation. There further has been provided an improved record formed by the method and system set forth above and utilizing the recording member therefor, the record having information stored therein in the form of surface deformations that are intaglio reproductions of the subject matter to be stored.

While all the foregoing specific examples have illustrated recording media comprising a photosensitive material dispersed or dissolved in a dielectric thermoplastic polymeric material, or in a dielectric organic liquid, it will be apparent to those skilled in the art that the recording media may be composed entirely of a material which possesses the requisite photosensitivity itself. Polymers of N-vinyl paraphenylazoaniline or paraphenylazo- 4-vinyl diphenylamine are examples of such materials.

While there have been described what are at present considered to be the preferred embodiments of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. The method of recording comprising the steps of providing an uncharged layer of solid thermoplastic dielectric material comprising a photosensitive substance dispersed therein and selected from the group consisting of halogenated hydrocarbons, azo compounds and aro- 32 a matic amines and characterized by the ability to produce electrical forces in response to exposure thereof to a pattern of activating radiation therefor sufficient to produce a corresponding pattern of deformation when said layer of dielectric material is in a deformable plastic state, exposing said layer of thermoplastic dielectric material to a selective pattern of said activating radiation to produce a corresponding electrical force pattern in said layer without an applied electric charge, and heating said solid thermoplastic dielectric material to bring it to a deformable plastic state and thereby record in said layer of dielectric material a pattern of deformation corresponding to said selective pattern of the activating radiation also without the application of an electric charge.

2. The method of recording set forth in claim 1, wherein said deformed layer of thermoplastic dielectric material is cooled to a solid condition to preserve on said surface layer a pattern of deformation corresponding to said selective pattern of the activating radiation.

' 3. The method of recording set forth in claim 1, including the further steps of permanently erasing said deformations of said surface by heating said deformed layer of thermoplastic dielectric material to the plastic condition thereof and exposing said plastic layer to a uniform pattern of said activating radiation to destroy the deformations in said surface and thereafter cooling said layer to the solid condition thereof, exposing said surface to a second selective pattern of said activating radiation to produce a corresponding second persistent electrical force pattern in said layer, heating said layer of thermoplastic dielecric material to the plastic condition thereof so that said second force pattern deforms said surface of said layer to produce a corresponding second image thereon without the aid of an applied electric charge, and cooling said deformed layer to the solid condition to preserve said deformations.

References Cited UNITED STATES PATENTS 3,081,165 3/1963 Ebert 96-1 3,268,361 8/1966 Gaynor 117-201 3,276,031 9/ 1966 Gaynor 346-74 3,291,601 12/1966 Gaynor 9.6-1.1

OTHER REFERENCES RCA Review, vol. 25, #4 December 1964, pp. 692-710.

GEORGE F. LESMES, Primary Examiner J. C. COOPER III, Assistant Examiner U.S. Cl. X.R. 

